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Using Seagate's new Laptop Thin Solid-State Hybrid Drive (SSHD) is a bittersweet experience.

Sweet because it indeed offers boot time and overall improvement somewhat similar to that of a solid-state drive (SSD) at a fraction of the cost, and bitter because its data transfer speed is slower than most regular hard drives'.

The Laptop Thin SSHD is designed specifically for laptops and supercompact desktops that focus on daily computing needs rather than data-moving-intensive tasks, and for this purpose, at the current cost of just $86 for 500GB, it delivers. You definitely don't want to use it as a secondary drive or in an external storage application, though.

If you're looking to upgrade your computer from a hard drive so the system will boot up faster, but don't want to invest in an SSD just yet, the Laptop Thin SSHD, as well as its predecessor, the 2nd-generation Momentus XT, is about the second best choice. The new drive also proves that SSHDs, for now, are not real alternatives to SSDs, such as these, for those who want uncompromising performance.

The new Laptop Thin SSHD is the third generation of hybrid drives from Seagate. The previous drives are the Momentus XT 750GB and Momentus XT 500GB. Starting at CES 2013, Seagate changed the way it names hybrid drives, now calling them all SSHDs. The designation Laptop Thin means that the drive is designed for laptops and comes in the newer 7mm thickness, compared with the 9.5mm thickness of previous drives and other standard laptop drives. There's also a Laptop SSHD that comes in the regular 9.5mm thickness, and a Desktop SSHD that has the 3.5-inch standard desktop design.

The new Laptop Thin SSHD's revised thickness means it now can fit in certain ultrabooks and also that its capacity is limited to just 500GB, which is the capacity of the first-generation drive. The Laptop SSHD drive, however, will offer the new 1TB capacity. This is because the Laptop Thin SSHD houses only a single platter, while the Laptop SSHD is thick enough to house two platters.

The new Laptop Thin SSHD (right) looks very similar to a Momentus regular hard drive, but 2.5mm thinner.
Dong Ngo/CNET

Similar to previous generations, the new Laptop Thin SSHD is a regular hard drive that has built-in 8GB of NAND flash memory, like the type of storage used in SSDs. The drive uses Seagate's Adaptive Memory Technology (AMT) that's designed to identify hot (frequently accessed) data and write it to the onboard flash memory part. The subsequent times the data is requested from the host, it will be read from the flash memory, and therefore will improve the access speed.

By design, AMT has to "learn" the patterns in which someone uses a computer and improvement is only observable in the subsequent times the same task is being executed. For example, once you have replaced a computer's hard drive with a Seagate SSHD, the first boot time might not show any difference at all. This proved to be trued in my testing, the test machine's boot time only improved (taking much shorter time) starting with the second boot.

On the other hand, the Laptop Thin SSHD is also quite different from the previous generation of Seagate hybrid drives. The first difference is the drive's spinning speed, which is now only 5,400rpm, as opposed to the Momentus drives' 7,200rpm. This means that the new drive is slower at data transferring, such as when copying a large amount of data from one drive to another, or from one place to another within itself. In fact, in my trial, it was about as slow as a regular 5,400rpm drive.

The second difference is that the NAND Flash memory part of the SSHD is now made of multilevel cell (MLC) NAND -- similar to the type used in most consumer-grade SSDs -- as opposed to the single-level cell (SLC) NAND, used in enterprise-grade SSDs. This helps lower the drive's cost but potentially means the flash memory part might become unreliable faster due to the lower write endurance (read more about that here), especially since the SSHD has only 8GB. In the future, there will be SSHDs with up to 32GB of flash memory.

Seagate says that the drive has algorithms that minimize the writing to the flash memory part and when used for its main purpose, as a main drive of a laptop or low-profile desktop, the SSHD's NAND flash memory part will outlast the drive's moving parts. This, of course, remains to be seen.

CNET editor Dong Ngo has been involved with technology since 2000, starting with testing gadgets and writing code for CNET Labs' benchmarks. He now manages CNET San Francisco Labs, reviews 3D printers, networking/storage devices, and also writes about other topics from online security to new gadgets and how technology impacts the life of people around the world.
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